An area deforested by illegal gold mining is seen in a zone known as Mega 14 in the Peruvian southern Amazon region of Madre de Dios.
Photograph: Janine Costa/Reuters

Peru has approved a law that would allow roads to be built in the most remote and pristine region of its Amazon rainforest, a haven for isolated indigenous groups and an area of primary forest rich in mahogany trees.

The law which declares the construction of roads in border zones of “national priority and interest” was announced in Peru’s official gazette just hours after Pope Francis ended a visit to the country in which he warned that the Amazon and its peoples had never been so under threat.

In an address in the jungle city of Puerto Maldonado on Friday, the pope railed against “pressure being exerted by big business interests” which were destroying a natural habitat vital for the entire planet.

But the law which promotes the construction of roads in Purus – an Amazon region near the border with Brazil – had already been approved by Peru’s congress and passed into law on Monday after no objections were raised by the country’s executive. The area encompasses four national parks and could affect five reserves for indigenous peoples living in “voluntary isolation”.

”The government clearly hasn’t reflected on the pope’s words,” said Lizardo Cauper, head of Peru’s federation of native Amazon peoples, Aidesep.

“These projects don’t benefit indigenous people. This is an area with isolated people who are extremely vulnerable,” he told the Guardian.

“Roads bring outsiders who traffic our land, log our timber, as well as drug traffickers and illegal miners,” he added.

The law contravenes several international commitments made by Peru including climate change pledges and trade agreements with the US and Europe.

“We have a state that makes decisions with its back to the Amazon and its indigenous peoples,” said Iván Lanegra, a former minister for indigenous affairs.

Julia Urrunaga, Peru director for Environmental Investigation Agency, said 95% of deforestation happens less than 6km from a road, adding the new law contradicted a court ruling that declared the protection of the forest in the national interest.

The network of roads, including the main 172-mile (277km) highway connecting Puerto Esperanza and Iñapari on the Brazilian border could result in the deforestation of 2,750 sq km, according to satellite mapping by Monitoring of the Amazon Andes Project.

“This law makes a mockery of Peru’s climate change commitments and the recent visit by the pope,” said Laura Furones of Global Witness.